1. Technical Field
The present invention relates to organic electroluminescent apparatuses and electronic apparatuses.
2. Related Art
Organic light-emitting diodes (OLEDs), i.e., organic electroluminescent (EL) devices included in thin and light self-luminous displays are attracting attention. An organic EL device includes at least one organic thin film layer composed of an organic material and held between a pixel electrode and a counter electrode, as disclosed in JP-A-2002-252083, for example.
Characteristics of organic thin films included in organic EL devices are easily altered and deteriorated by oxygen or moisture. Such alteration and deterioration of characteristics shortens the lifetime of organic EL devices. Deterioration of organic thin films tends to occur first in a peripheral region of a element area that easily allow entry of oxygen or moisture. However, it takes time before organic thin films provided in a central region of the element area start to be deteriorated. This means that, while light-emitting elements in the central region are still capable of emitting light, light-emitting elements in the peripheral region may become incapable of emitting light. In such an event, an organic EL apparatus itself becomes unusable (a first problem).
Organic thin films can be formed by, for example, an application method, in which a solution, i.e., ink, containing a material for organic thin films (such as functional polymer) and a solvent is applied to a substrate and is dried thereon.
In general, the drying rate of ink tends to be higher in a peripheral region of the substrate than in a central region of the substrate. This is because the concentration of the solvent in an atmosphere around the peripheral region of the substrate tends to be lower than that in an atmosphere above the central region of the substrate. Such nonuniformity in the drying rate often triggers nonuniformity in the thickness of organic thin films to be formed. Further, nonuniformity in the thickness of organic thin films often triggers nonuniformity in the brightness and color of light to be emitted.
In view of such circumstances, a technique is disclosed in JP-A-2002-252083 in which a group of dummy banks are provided around a display pixel area (an effective optical area), in the same shape and at the same pitches as those for display pixels, and an ink composition containing an organic EL material is applied not only to the display pixel area but also to the region around the display pixel area, whereby organic EL thin films are formed. In this technique, since the ink composition is also applied to the dummy area around the display pixel area, the concentration of a solvent in an atmosphere above the display pixel area can be made almost uniform. Thus, the drying rates of ink in individual pixels arranged in the display pixel area can be made almost uniform. Consequently, nonuniformity in the thickness of the organic thin films can be reduced. The organic thin films formed in the dummy area, i.e., the organic thin films formed in the peripheral region of the substrate, are not used for light emission. Therefore, difference between the thicknesses of the organic thin films in the peripheral region of the substrate and in the display pixel area does not affect the light emission characteristic.
In the organic EL apparatus disclosed in JP-A-2002-252083, however, a belt-like space having a width of several millimeters needs to be reserved for the dummy area on the substrate on which organic EL devices are to be formed. Reservation of such a space prevents reduction in the frame width of the organic EL apparatus (a second problem).